/* * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */#include "precompiled.hpp"#include "gc_implementation/g1/concurrentMarkThread.inline.hpp"#include "gc_implementation/g1/g1CollectedHeap.inline.hpp"#include "gc_implementation/g1/g1CollectorPolicy.hpp"#include "gc_implementation/g1/g1Log.hpp"#include "gc_implementation/g1/vm_operations_g1.hpp"#include "gc_implementation/shared/gcTimer.hpp"#include "gc_implementation/shared/gcTraceTime.hpp"#include "gc_implementation/shared/isGCActiveMark.hpp"#include "gc_implementation/g1/vm_operations_g1.hpp"#include "runtime/interfaceSupport.hpp"VM_G1CollectForAllocation::VM_G1CollectForAllocation(uint gc_count_before, size_t word_size) : VM_G1OperationWithAllocRequest(gc_count_before, word_size, GCCause::_allocation_failure) { guarantee(word_size != 0, "An allocation should always be requested with this operation.");}void VM_G1CollectForAllocation::doit() { G1CollectedHeap* g1h = G1CollectedHeap::heap(); GCCauseSetter x(g1h, _gc_cause); _result = g1h->satisfy_failed_allocation(_word_size, allocation_context(), &_pause_succeeded); assert(_result == NULL || _pause_succeeded, "if we get back a result, the pause should have succeeded");}void VM_G1CollectFull::doit() { G1CollectedHeap* g1h = G1CollectedHeap::heap(); GCCauseSetter x(g1h, _gc_cause); g1h->do_full_collection(false /* clear_all_soft_refs */);}VM_G1IncCollectionPause::VM_G1IncCollectionPause(uint gc_count_before, size_t word_size, bool should_initiate_conc_mark, double target_pause_time_ms, GCCause::Cause gc_cause) : VM_G1OperationWithAllocRequest(gc_count_before, word_size, gc_cause), _should_initiate_conc_mark(should_initiate_conc_mark), _target_pause_time_ms(target_pause_time_ms), _should_retry_gc(false), _old_marking_cycles_completed_before(0) { guarantee(target_pause_time_ms > 0.0, err_msg("target_pause_time_ms = %1.6lf should be positive", target_pause_time_ms)); _gc_cause = gc_cause;}bool VM_G1IncCollectionPause::doit_prologue() { bool res = VM_G1OperationWithAllocRequest::doit_prologue(); if (!res) { if (_should_initiate_conc_mark) { // The prologue can fail for a couple of reasons. The first is that another GC // got scheduled and prevented the scheduling of the initial mark GC. The // second is that the GC locker may be active and the heap can't be expanded. // In both cases we want to retry the GC so that the initial mark pause is // actually scheduled. In the second case, however, we should stall until // until the GC locker is no longer active and then retry the initial mark GC. _should_retry_gc = true; } } return res;}void VM_G1IncCollectionPause::doit() { G1CollectedHeap* g1h = G1CollectedHeap::heap(); assert(!_should_initiate_conc_mark || g1h->should_do_concurrent_full_gc(_gc_cause), "only a GC locker, a System.gc(), stats update, whitebox, or a hum allocation induced GC should start a cycle"); if (_word_size > 0) { // An allocation has been requested. So, try to do that first. _result = g1h->attempt_allocation_at_safepoint(_word_size, allocation_context(), false /* expect_null_cur_alloc_region */); if (_result != NULL) { // If we can successfully allocate before we actually do the // pause then we will consider this pause successful. _pause_succeeded = true; return; } } GCCauseSetter x(g1h, _gc_cause); if (_should_initiate_conc_mark) { // It's safer to read old_marking_cycles_completed() here, given // that noone else will be updating it concurrently. Since we'll // only need it if we're initiating a marking cycle, no point in // setting it earlier. _old_marking_cycles_completed_before = g1h->old_marking_cycles_completed(); // At this point we are supposed to start a concurrent cycle. We // will do so if one is not already in progress. bool res = g1h->g1_policy()->force_initial_mark_if_outside_cycle(_gc_cause); // The above routine returns true if we were able to force the // next GC pause to be an initial mark; it returns false if a // marking cycle is already in progress. // // If a marking cycle is already in progress just return and skip the // pause below - if the reason for requesting this initial mark pause // was due to a System.gc() then the requesting thread should block in // doit_epilogue() until the marking cycle is complete. // // If this initial mark pause was requested as part of a humongous // allocation then we know that the marking cycle must just have // been started by another thread (possibly also allocating a humongous // object) as there was no active marking cycle when the requesting // thread checked before calling collect() in // attempt_allocation_humongous(). Retrying the GC, in this case, // will cause the requesting thread to spin inside collect() until the // just started marking cycle is complete - which may be a while. So // we do NOT retry the GC. if (!res) { assert(_word_size == 0, "Concurrent Full GC/Humongous Object IM shouldn't be allocating"); if (_gc_cause != GCCause::_g1_humongous_allocation) { _should_retry_gc = true; } return; } } _pause_succeeded = g1h->do_collection_pause_at_safepoint(_target_pause_time_ms); if (_pause_succeeded && _word_size > 0) { // An allocation had been requested. _result = g1h->attempt_allocation_at_safepoint(_word_size, allocation_context(), true /* expect_null_cur_alloc_region */); } else { assert(_result == NULL, "invariant"); if (!_pause_succeeded) { // Another possible reason reason for the pause to not be successful // is that, again, the GC locker is active (and has become active // since the prologue was executed). In this case we should retry // the pause after waiting for the GC locker to become inactive. _should_retry_gc = true; } }}void VM_G1IncCollectionPause::doit_epilogue() { VM_G1OperationWithAllocRequest::doit_epilogue(); // If the pause was initiated by a System.gc() and // +ExplicitGCInvokesConcurrent, we have to wait here for the cycle // that just started (or maybe one that was already in progress) to // finish. if (_gc_cause == GCCause::_java_lang_system_gc && _should_initiate_conc_mark) { assert(ExplicitGCInvokesConcurrent, "the only way to be here is if ExplicitGCInvokesConcurrent is set"); G1CollectedHeap* g1h = G1CollectedHeap::heap(); // In the doit() method we saved g1h->old_marking_cycles_completed() // in the _old_marking_cycles_completed_before field. We have to // wait until we observe that g1h->old_marking_cycles_completed() // has increased by at least one. This can happen if a) we started // a cycle and it completes, b) a cycle already in progress // completes, or c) a Full GC happens. // If the condition has already been reached, there's no point in // actually taking the lock and doing the wait. if (g1h->old_marking_cycles_completed() <= _old_marking_cycles_completed_before) { // The following is largely copied from CMS Thread* thr = Thread::current(); assert(thr->is_Java_thread(), "invariant"); JavaThread* jt = (JavaThread*)thr; ThreadToNativeFromVM native(jt); MutexLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); while (g1h->old_marking_cycles_completed() <= _old_marking_cycles_completed_before) { FullGCCount_lock->wait(Mutex::_no_safepoint_check_flag); } } }}void VM_CGC_Operation::acquire_pending_list_lock() { assert(_needs_pll, "don't call this otherwise"); // The caller may block while communicating // with the SLT thread in order to acquire/release the PLL. SurrogateLockerThread* slt = ConcurrentMarkThread::slt(); if (slt != NULL) { slt->manipulatePLL(SurrogateLockerThread::acquirePLL); } else { SurrogateLockerThread::report_missing_slt(); }}void VM_CGC_Operation::release_and_notify_pending_list_lock() { assert(_needs_pll, "don't call this otherwise"); // The caller may block while communicating // with the SLT thread in order to acquire/release the PLL. ConcurrentMarkThread::slt()-> manipulatePLL(SurrogateLockerThread::releaseAndNotifyPLL);}void VM_CGC_Operation::doit() { TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty); GCTraceTime t(_printGCMessage, G1Log::fine(), true, G1CollectedHeap::heap()->gc_timer_cm(), G1CollectedHeap::heap()->concurrent_mark()->concurrent_gc_id()); SharedHeap* sh = SharedHeap::heap(); // This could go away if CollectedHeap gave access to _gc_is_active... if (sh != NULL) { IsGCActiveMark x; _cl->do_void(); } else { _cl->do_void(); }}bool VM_CGC_Operation::doit_prologue() { // Note the relative order of the locks must match that in // VM_GC_Operation::doit_prologue() or deadlocks can occur if (_needs_pll) { acquire_pending_list_lock(); } Heap_lock->lock(); SharedHeap::heap()->_thread_holds_heap_lock_for_gc = true; return true;}void VM_CGC_Operation::doit_epilogue() { // Note the relative order of the unlocks must match that in // VM_GC_Operation::doit_epilogue() SharedHeap::heap()->_thread_holds_heap_lock_for_gc = false; Heap_lock->unlock(); if (_needs_pll) { release_and_notify_pending_list_lock(); }}